Friction and wear of polyimide thin films

The friction and wear of thin polyimide films were measured as functions of the polyimide structure, the sliding speed and the temperature in a pin-on-disk machine. A 5 N load pressed a stationary 52100 steel ball against the rotating polyimide film 50 μm thick which was solvent cast on an AISI 410 stainless steel disk. The wear rates were significantly affected by structural differences which resulted from the different dianhydrides and diamines from which the polyimides were synthesized. The wear rates were lowest for the most flexible molecular chains as indicated by the glass transition temperatures. A positive correlation was found for a power law relationship between the wear rate and the elastic modulus (the correlation coefficient was 0.997) for tests at 24 and 130°C. The power law relationship is suggested by the fatigue model of wear.